The present invention relates generally to seals for containers such as bottles and the like. More specifically, the present invention relates to seals for containers having caps.
In the packaging of certain products, such as bottled products or products provided in jars and other small containers, it is desirable to provide a seal that retains the freshness of the contents and further which indicates whether the seal has been tampered with.
One suitable seal system that indicates whether the seal has been tampered with and further that retains the freshness of the contents disposed within the container is an induction foil lining system. Such induction foil lining systems have been used in the container closure industry for at least 20 years. Currently available foil lining systems include an adhesive layer that attaches a pulp or backing layer to the inside surface of the cap. The backing layer is attached to a foil layer by a coating of wax disposed between the backing and the foil layer. The foil layer is attached to the rim of the container with a heat seal layer.
During assembly, the backing layer of the backing layer/wax layer/foil layer/heat seal layer structure is attached to the inside surface of the cap with the adhesive, often a hot melt adhesive. The cap is then screwed onto the rim of the container so that the heat seal layer that coats the foil layer engages the rim of the container. The assembled container is then passed under an induction heating apparatus which heats the foil layer, resulting in a melting of the heat seal layer and the bonding of the foil layer to the rim of the container. The wax melts and is absorbed into the backing.
When the consumer unscrews the cap from the container, cleavage occurs at the wax layer whereby the backing layer remains attached to the inside surface of the cap and the foil layer layer remains attached to the rim of the container. After the consumer removes the foil layer to obtain access to the product, the backing layer provides a gasket seal between the inside surface of the cap and the rim when the consumer screws the cap back onto the container.
As noted above, currently available foil sealing systems rely upon the incorporation of wax into the sealing structure between the backing layer and the foil seal. Wax is used because it can be readily absorbed into the porous backing layer which reliably allows the backing layer to separate from the foil layer when the consumer unscrews the cap. The use of glue or adhesive instead of wax would make it difficult to remove or separate the cap and the backing layer from the foil seal.
The use of wax, however, is problematic because at least some wax will inevitably remain on the lower surface of the backing layer where it has the opportunity to contaminate the product disposed within the container. Further, container manufacturers are often confronted with the problem of a lack of availability of suitable wax for uses in such sealing systems. Still further, the wax coated backing layer often provides an unreliable gasket seal between the cap and the rim of the container because the wax coating often does not always provide an effective barrier to fluids over the backing layer. A fluid barrier is needed because the backing layer is typically made from a pulp material, which is absorbent.
Accordingly, there is yet to be an effective foil seal system which provides combination of an effective gasket seal between a container lid or cap and the rim of a container which also incorporates a heat or foil seal over the rim of the container and which also does not rely upon the use of wax to removably attach the foil layer to the backing.
Still further, drug manufacturers and food manufacturers have a strong preference for providing a foil seal on the lip or rim of the container which provides an exposed foil surface to the consumer after the consumer removes the cap or lid. Accordingly, it would be beneficial to provide an improved wax-free foil seal system which provides an improved gasket seal between the inside surface of the cap and the rim of the container after the foil seal has been removed, which further provides a foil seal over the rim of the container which includes an exposed upper surface of foil upon removal of the cap or lid from the container.
Accordingly, a need exists for an improved foil sealing system which provides both an improved gasket seal between the container lid or cap and the rim of the container as well as an exposed foil seal over the rim of the container and which does not rely upon the use of wax for connecting the backing layer to the foil layer.